1. Field of the Invention
The present invention relates to a ratchet device, and more particularly to a ratchet device with stable structure.
2. Description of Related Art
A conventional ratchet device comprises a control unit 21. The control unit 21 has a central hole 211 opened there through. Two pairs of side grooves (a first side groove 212A, a second side groove 212B, a third side groove 213A, a fourth side groove 213B) defined on two sides of the central hole 211 of the control unit 21. The side grooves 212A, 212B, 213A, 213B communicates with the central hole 211. A first elastomer 22A, a second elastomer 22B, a third elastomer 23A and a fourth elastomer 23B are respectively received in the first side groove 212A, the second side groove 212B, the third side groove 213A and the fourth side groove 213B. A first blocker 24A, a second blocker 24B, a third blocker 25A and a fourth blocker 25B are respectively received in the first side groove 212A, the second side groove 212B, the third side groove 213A and the fourth side groove 213B. A first protrusion 241A, a second protrusion 241B, a third protrusion 251A and a fourth protrusion 251B are respectively extruded at one ends of the first blocker 24A, the second blocker 24B, the third blocker 25A and the fourth blocker 25B. A first engaging portion 242A, a second engaging portion 242B, a third engaging portion 252A and a fourth engaging portion 252B are respectively formed at another ends of the first blocker 24A, the second blocker 24B, the third blocker 25A and the fourth blocker 25B. The control unit 21 has a receiving hole 214 opened on the outside periphery thereof. The receiving hole 214 receives a fifth elastomer 26 and a bead 27. A ratchet unit 28 is located in the central hole 211 of the control unit 21. A polygonal hole 281 is opened at one end of the ratchet unit 28. A plurality of teeth 282 are formed around the periphery of the ratchet unit 28. The engaging portions 242A, 242B, 252A, 252B engage with the teeth 282. The control unit 21 is encircled by a switching unit 29. The switching unit 29 has a first push portion 291A, a second push portion 291B, a third push portion 292A and a fourth push portion 292B, those are respectively corresponding to the first protrusion 241A, the second protrusion 241B, the third protrusion 251A and the fourth protrusion 251B. When the push portions 291A, 291B, 292A, 292B push against the protrusions 241A, 241B, 251A, 251B respectively, the blockers 24A, 24B, 25A, 25B move along the side grooves 212A, 212B, 213A, 213B respectively. A first engaging groove 293A, a second engaging groove 293B and a third engaging groove 293C are defined on the inner periphery of the switching unit 29. The bead 27 of the control unit 21 is selectively engaged with one of the engaging grooves 293A, 293B, 293C. When a user rotates the switching unit 29 clockwise, the third push portion 292A and the fourth push portion 292B of the switching unit 29 push against the third blocker 25A and the fourth blocker 25B respectively, and the third blocker 25A and the fourth blocker 25B move along the third side groove 213A and the fourth side groove 213B respectively, so that the third engaging portion 252A and the fourth engaging portion 252B are disengaged with the teeth 282, and the first engaging portion 242A and the second engaging portion 242B keep being engaged with the teeth 282, thereafter the bead 27 is engaged with the first engaging groove 293A. Under this arrangement, when the user rotates the control unit 21 clockwise to operate, the ratchet unit 28 rotates with the rotation of the control unit 21, because the first engaging portion 242A and the second engaging portion 242B are engaged with the teeth 282; when the user rotates the control unit 21 counterclockwise to operate, the ratchet unit 28 does not rotate with the rotation of the control unit 21 because the first engaging portion 242A and the second engaging portion 242B are respectively moved toward the first elastomer 22A and the second elastomer 22B by the pushing from the teeth 282. Thus, the first engaging portion 242A and the second engaging portion 242B are disengaged with the teeth 282 step by step by the compression of the first elastomer 22A and the second elastomer 22B. However, the conventional ratchet device has one shortcoming as following:
Because the engaging faces between one pair of the engaging portions 242A, 242B, 252A, 252B and the teeth 282 are too few to make the engagement between one pair of the engaging portions 242A, 242B, 252A, 252B and the teeth 282 stable for suffering a large torsion. The engaging portions 242A, 242B, 252A, 252B or the teeth 282 might be broken if the external torsion were over the strength of the structure among the engaging portions 242A, 242B, 252A, 252B and the teeth 282.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional. Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.